Administration of the MapR-DB is done primarily via the commmand line (maprcli) or with the MapR Control System (MCS).
Regardless of whether the MapR-DB table is used for binary files or JSON documents, the same types of commands are used
with slightly different parameter options. MapR-DB administration is associated with tables, columns and column families,
and table regions.

Adding Roles to a Node

You can add roles on a node after you deploy the node in a cluster. The process of adding a
role to a node involves installing a package on the node and updating the cluster to recognize
the new role. The process for adding a role depends on the role type.

Once you have added a role to a node, you must restart Warden. Observe the following best
practices when restarting Warden on ZooKeeper and CLDB nodes:

Perform a rolling restart of Warden to ensure that all services are up. A rolling restart of
Warden means restart Warden on each node, one at a time, pausing until the last restart
finishes before beginning the next.

To avoid a failover from occurring, identify nodes running critical services, such as
JobTracker or ResourceManager, and restart Warden last on those nodes.

Restart Warden on nodes that run critical cluster services, such as JobTracker or
ResourceManager, during periods of low activity.